Powering the Waterjet

THE HYDRAULIC WATER JET INTENSIFIER PUMP

The waterjet intensifier pump acts as an amplifier as it converts the energy from the low-pressure hydraulic fluid into ultra-high pressure water. The hydraulic system provides fluid power to a reciprocating piston in the intensifier center section. A limit switch, located at each end of the piston travel, signals the electronic controls to shift the directional control valve and reverse the piston direction.

The intensifier assembly, with a plunger on each side of the piston, generates pressure in both directions. As one side of the intensifier is in the inlet stroke, the opposite side is generating ultra-high pressure output. During the plunger inlet stroke, filtered water enters the high pressure cylinder through the check value assembly. After the plunger reverses direction, the water is compressed and exits as ultra-high pressure water and then enters the pressure vessel (attenuator). The attenuator smoothes pressure fluctuations from the intensifier and delivers a constant and steady stream of ultra-high pressure water to the cutting or cleaning tool.

THE DIRECT DRIVE WATER JET PUMP

Jet Edge’s Eco-Jet direct drive positive displacement pump utilizes an electric motor to power a plunger pump. Drive belts connect pulleys on the electric motor and the plunger pump. The drive belts rotate a crank shaft in the plunger pump. The crank shaft cycles three pistons; each piston is connected to a plunger that produces ultra high pressure water in a high pressure assembly.

The crankshaft driven piston inside the plunger pump cycles a plunger in and out of a high pressure cylinder. When the plunger is pulled from the high pressure cylinder, the low pressure cycle begins. When the plunger is pushed into the high pressure cylinder the high pressure cycle begins. The pressure in the high pressure cylinder increases to overcome the spring pressure on the high pressure poppet. The high pressure poppet moves away from the seat allowing UHP water to flow past the high pressure poppet. The UHP water is output through UHP tubing to an attenuator and made available to a water tool connected to the UHP water circuit.

Every waterjet shop wants to produce their parts at the lowest possible cost. To achieve this objective, nothing is more important than a correctly sized waterjet pump.

But selecting the perfect pump to power your waterjet system can be a mind-boggling task. There are so many choices and considerations to make. Do I need a hydraulic intensifier pump or can I get by with a cheaper direct drive pump? How much pressure do I need? How much horsepower? The list goes on…

To help you make an informed purchasing decision, we have put together this short guide. For more information, please consult with your Jet Edge regional sales manager.

What’s Your Application?

Picking the perfect pump always begins by identifying your specific application. This will help your waterjet pump manufacturer determine your pressure, horsepower, flow rate and other requirements. What are you cutting? How fast do you need to cut the product? Can we make your throughput requirements with a single nozzle? Does the application require multiple nozzles? Can the cutting application be performed with straight water? Does the application require the addition of abrasive?

A reputable waterjet manufacturer will always help their customer determine the most efficient and cost-effective pump for their application.

The All Important Test Cut

Most waterjet manufacturers offer free test cuts to help their customers determine the appropriate pump and motion system set up for their application. During the test cut, the manufacturer will run a series of tests to determine the most efficient cutting pressure, horsepower, and speed to achieve the customer’s throughput requirements.

During the test, we determine if we can process the customer’s material with straight water or if we need to add abrasive. We also determine how much pressure and what orifice size and how many cutting heads are required to make their throughput requirements. If the application requires abrasive, we will determine how much abrasive is required and the most efficient orifice/nozzle combination. Once we have determined these factors, we can size the pump and flow rate.

The test cut will help you select the most cost-effective pump for your application and also will arm you with cutting data that will help you keep operating costs as low as possible by running your system at the most cost-efficient pressure, using the least amount of abrasive necessary and running the appropriate number of cutting heads to achieve desired throughput.

Intensifier vs. Direct Drive

There are two basic types of waterjet pumps, direct drive pumps (also known as positive displacement or crank pumps) and hydraulic intensifier pumps. A direct drive pump uses a crank to drive the pump’s plunger, while an intensifier uses a hydraulic cylinder to drive the plunger. Direct drive pumps cost less than hydraulic pumps up front, but require much more maintenance. They are a good economical alternative for shops that only require an entry level system for low-volume cutting. Intensifier pumps are recommended for shops that need to process higher volumes of material and thicker materials.

Extreme Cutting Pressures

In the last few years, waterjet pump manufacturers have begun offering pumps with operating pressures exceeding 90,000 psi. These extreme pressure pumps cost more up front than 60,000 psi pumps, but can greatly increase productivity and can lower operating costs as much as 40% by cutting faster and using less electricity, water and garnet.